Prove that Armstrong’s transitivity axiom is sound—that is, every relation that satis?es the FDs X ? Y and Y ? Z must also satisfy the FD X ? Z .

Consider a relation r and an arbitrary pair of its tuples t , s ? r.


If X ? Y and t , s agree on every attribute of X ,then t , s agree on every attribute of Y . Because of Y ? Z and since t , s agree on every attribute of Y , they must agree on every attribute of Z . Thus, every pair of tuples that agrees on X must also agree on Z ,so X ? Z holds.

Computer Science & Information Technology

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Method shuffle is a member of __________.

a. class Arrays. b. class Collections. c. interface Collection. d. Interface List.

Computer Science & Information Technology

Choosing ________ for row labels and column headings will save room on charts

Fill in the blank(s) with correct word

Computer Science & Information Technology

If the lowest annual fee at a discount warehouse is $20.25 and the highest is $55.50, a(n) ____________________ on the Annual Fee field ensures it is a value between $20.25 and $55.50.

Fill in the blank(s) with the appropriate word(s).

Computer Science & Information Technology

The text box property that specifies the color of the text inside the text box is called the ____ property.

A. ForeColor B. FontColor C. TextColor D. CharacterColor

Computer Science & Information Technology